An Experimental Study on Friction Stir Processing of AA-6061 Aluminum Alloy

Friction stir processing (FSP) has promised for application of thermo mechanical processing techniques where aims to change the microstructural and mechanical properties of materials in order to obtain high performance and reducing the production time and cost. In this study, friction stir processing on cold worked 6061 Aluminum alloy was employed. The ratio of rotational and translational speed (ω/f) was varied from 22 to 125 (rev/mm). The effect of the said parameter on the microstructure and mechanical properties was examined. The results show that FSP reduces the grain size in operational zone. Grain size decreases as ω/f increases. To a certain range of ω/f from 22 to 28 average hardness decrease and for range of ω/f from 22 to 25 tensile strength decreases which correspondingly causes increase in toughness and ductility of cold worked material. However, afterwards range of ω/f from 28 to 125 for average hardness and range of ω/f from 25 to 125, the trend becomes reverse. The effect of above parameter on surface quality was also observed visually. It has been found that within investigated range, the surface finish enhances with increasing ω/f. The result of microstructure shows that operation zones have small grain size with undefined directions. The effect of the multi passing (from 2 to 4) on grain size was also investigated. It was found that with increasing the number of passes, the size of grains decreases. Keywords: Friction Stir Processing, Microstructure, Hardness, Tensile, Impact, Quality, AL6061.